Teaching with Weathering Videos

Some weathering processes proceed so slowly in time that even on a human lifetime we would notice very little change, such as for the height of a mountain. Other weathering processes are catastrophic and may occur and end within a matter of minutes.

Video snips of catastrophic weathering events are particularly instructive because they show dynamic change in material properties, such as particle shape (think physical weathering), or composition (think chemical weathering).

Physical Weathering - Fragment Weathering During Movement

Video Tutorial - Physical Weathering on the World's Most Dangerous Ride

Instructions to Student:

This adventurer is on a motorbike trip through the Himalayan Mountains when he meets a road crew building a section of highway. Carefully observe the boulders cascading down the steep slope to the river below, and address the following questions. Watch and listen carefully, write your observations,and discuss the issues with your peers.

  • Observe the rock fragments around the bulldozer. These were created by blasting explosives into the slope. Describe sizes and shapes of the largest fragments.
  • Describe any change(s) to the size and shape of the largest fragments as they move down the slope.
  • Observe and describe the motion of the largest boulder as it moves down the slope. Does it slide, roll, etc.? Is it always in contact with the ground? (After all, it weighs hundreds and hundreds of pounds).
  • The bulldozer moves one large boulder. Describe how that large boulder interacts with other fragments in motion on the slope.
  • Notice the river at the base of this slope. The water is relatively shallow, at least compared to the largest boulders which cause the whitewater flow at the surface. What are the possible sources of the boulders resting on the river bottom, that is, where might they have come from?
  • This slope may be on the order of 100 yards in length. What differences in the size, shapes, and deposits of sediment might occur for longer slopes in these mountains – say on the order of 1 mile or more? How about a shorter slope?
  • Suppose there were no river at the bottom of the slope. You're doing a geologic survey of the debris at the bottom of the ravine (no river). Write a short description of how the deposit there might differ from the bedload deposit in the river. How might the deposit in this dry ravine look, if different, if it were 100 years old? 1,000 years old? 1,000,000 years old?

Click to download the video tutorial shown below.


Chemical Weathering

Rocks and minerals exposed near and at the Earth's surface are subject to many chemically reactive compounds, such as atmospheric oxygen, carbon dioxide, and rainfall, all of which are capable of breaking chemical bonds in those solid materials. Over geologic time, rocks and minerals are broken down into smaller fragments and partially or wholly dissolved, and many new materials are formed over time, such as clay in soil.

In this video, geologic materials in the mountains are weathered both physically and chemically, transported down slope into nearby valleys, and deposited and weathered to form a diversity of soils. The importance of these soils for the growth of grape vines and production of wine is the subject of this video and tutorial.

Video Tutorial - Weathering and Wine

Instructions to Student

The Napa Valley in California is known as one of the great wine producing regions in the world. Why? What factors in nature occur that resulted in this reputation? Watch and listen carefully, write your observations, descriptions, and discuss these issues with your peers.

  • About how old are the rocks of the Napa mountain ranges?
  • What was the depositional environment in which the rocks of the Napa mountain ranges formed?
  • What forces or events transformed the original environment of deposition into the environment of the Napa Valley of today?
  • Is the landscape of the Napa Valley characterized primarily as a) mostly slopes, b) mostly flat valley floors, or c) a diverse mixture of slopes and valley floors?
  • How is the diversity of soil types in Napa Valley described?
  • What factors would you cite to explain the diversity of soil types found in the Napa Valley?
  • How is the relationship described between the number of varieties of grape and the number of different soil types in the Napa Valley?
  • Now look at the big picture and summarize – In terms of the environment, landscape, rock, soil, and geologic history, why is the Napa Valley one of the premier wine-growing regions of the world?